Electric lamp with refractory metal components connected to molybdenum foils

ABSTRACT

An envelope of glass of high silica content, such as quartz glass or similar, has molybdenum foils pinch-sealed into the lamp envelope. Lamp components of refractory material, such as molybdenum, or tungsten are welded to the foils, for example by ultrasonic welding, by interposition of an intermediate layer of aluminum foil, for example up to 0.1 mm. thickness.

United States Patent Wiedenmann v [451 Oct. 31, 1972 [541 ELECTRIC LAMP WITH REFRACTORY METAL COMPONENTS CONNECTED TO MOLYBDENUM FOILS [72] Inventor: Hans Wiedenmann, Heidenheim,

Germany [73] Assignee: Patent-Trenliand-Gesellschaft fur elektrische Gluhlampen mbH,

Munich, Germany 7 [221 Filed: o:.21,197o

211 Appl. No.: 82,685

[30] Foreign Application Priority Data Nov. 20, 1969 Germany ..P 19 56 484.2

[52] US. Cl ..313/332, 287/75 [51] Int. Cl ..Hlj 5/00 [58] Field of Search ..313/332; 287/75 [56] I References Cited UNITED STATES PATENTS 3,346,768 10/1967 Patsch ..313/332 X 2,341,716 2/1944 Herdman ..313/332 X Primary Examiner-David Schonberg Assistant Examiner-Paul A. Sacher Attorney-Flynn & Frishauf [571 ABSTRACT An envelope of glass of high silica content, such as quartz glass or similar, has molybdenum foils pinchsealed into the lamp envelope. Lamp components of refractory material, such as molybdenum, or tungsten are welded to the foils, for example by ultrasonic welding, by interposition of an intermediate layer of aluminum foil, for example up to 0.1 mm. thickness.

6 Claims, 3 Drawing Figures PATEN TEU B 3,701,921

I l l L. .J j

no.1 I FIG. 2

FIG. 3

v Hans Wiedenmann INVENTOR ELECTRIC LAMP WITI-I REFRACTORY METAL COMPONENTS CONNECTED TO MOLYBDENUM FOILS The present invention relates to an electric lamp comprising an envelope of quartz glass or some other glass of high silica content, having molybdenum foils pinch-sealed into the lamp envelope, and lamp components of a refractory metal, more particularly of molybdenum or tungsten, welded to the two ends of said foils; and to a method for producing the welds.

In lamps of this type, it is well-known to use platinum (which is expensive) as an intermediate layer to weld the lamp components to the ends of the molybdenum foils which are pinch-sealed into the lamp envelope. This known process provides a stable weld which is reliable and durable in operation of the lamps and which is heat-resistant, particularly to the high temperature occurringduring the pinch-sealing of the molybdenum foils into the lamp envelope.

US. Pat No. 3,455,015 describes .a method and device for ultrasonically welding a ductile metal such as aluminum or copper, to a hard material such as glass or other glass-like or ceramic materials, or to a metal such as tungsten or molybdenum.

Unexpectedly, it has been found that by welding the lamp components to the ends of the molybdenum foils which are pinch-sealed into the lamp envelope when using the less expensive aluminum as an intermediate layer, a weld is obtained which is equivalent to a weld with platinum as an intermediate layer, with regard to its solidity and durability during operation of the lamps. Further, the weld with aluminum possesses the same high temperature-resistance as the weld with platinum when pinch-sealing the molybdenum foils into the lamp envelope, although, as is well-known, the melting point of aluminum is considerably below the temperature which prevails during pinch-sealing of the molybdenum foils into the lamp envelope.

SUBJECT MATTER OF THE INVENTION A lamp envelope of quartz, glass or some other glass of high silica content, has molybdenum foils pinchsealed into the lamp envelope, and lamp components of a refractory metal, more particularly of molybdenum or tungsten, are welded to the two ends of said foils. In accordance with the invention, at least the lamp components extending externally of the lamp such as leadin wires or base pins, are welded to the pinch-sealed molybdenum foils by interposition of aluminum. Preferably, the welding is effected by ultrasonics.

The invention will be described by way of example with reference to the accompanying drawings, wherein:

FIG. 1 is a schematic vertical cross sectional view of an electric lamp such as, for instance, a halogen incandescent lamp in accordance with the invention;

FIG. 2 shows the same lamp turned about 90; and

FIG. 3 is a schematic diagram of a welding device.

The halogen incandescent lamp 1 has a light-transmissive envelope such as quartz glass, one end of which is sealed by an exhaust tip 2 and the other end by flat pinching. The lamp is filled with an inert gas such as nitrogen, and with a halogen additive such as hydrogen bromide.

Two molybdenum foils 4 are pinch-sealed into the flat pinch 3, and are welded by ultrasonics to the base ins 7 b usin an aluminum foil 16' as an intermediate ayer. T e tlnc ness of the aluminum foil may be up to 0.1 mm. The thickness of the molybdenum foils is about 15 to 60 u.

The ends of a tungsten filament 5 are welded to the molybdenum foils 4 in known manner by using an intermediate layer 6 of aluminum. The aluminum may be used in form of a foil or as a powder, which is formed to a paste. by a volatile vehicle. The welding of the filament ends to the molybdenum foils 4 is effected by ultrasonics.

FIG. 3 is a schematic view of an ultrasonic generator 8 with a mechanical amplitude transformer, or horn 9, for instance of steel. The horn has a bore 10, into which a cylindrical body 11, for instance of steel, with a frustoconical tip 12 is inserted. A hard body 14 consist-' ing for instance of sintered alumina, with a particle size of from 3 to 5 11., is pressed into a bore 13 of tip 12.

For producing the weld, the flat pinched end portion of the base pin 7 is laid on an anvil 15 of hard metal. An aluminum foil 16 is located on the base pin, and thereon the molybdenum foil 4. Instead of an aluminum foil, aluminum powder mixed with ethanol to form a paste may also be used. The molybdenum foil and the base pin are overlapping by up to approximately 5 mm. Then the components are welded by ultrasonics at a horn pressure of 25 40 kg/cm The rough surface of the alumina body 14 prevents v gliding ofthe horn tip on the molybdenum foil during operation.

I claim:

1. In an electric lamp having an envelop of glass of high silica content, molybdenum foils (4) pinch-sealed into the lamp envelope, and elements of a refractory metal welded to the ends of said foils,

the improvement comprising aluminum interposed, at the weld, between the pinch-sealed molybdenum foils and at least the elements extending externally of the lamp.

2. Lamp according to claim I, wherein the interposed aluminum is a layer of aluminum foil of up to 0.1 mm. thickness.

3. Lamp according to claim 1, wherein the thickness of the pinch-sealed molybdenum foils is about 15 to 60 4. Lamp according to claim 1 wherein the lamp has internally positioned elements and aluminum is interposed in welds between the pinch-sealed molybdenum foils and the elements positioned internally of the lamp. 5. Lamp according to claim 1, wherein the elements of refractory metal include molybdenum and tungsten.

6. Lamp according to claim 1, wherein the elements of refractory material include lead-in wires or base pins.

qgz gg UNITED 51mm mum Un V ERWHCATE @F 'QGRREQTWN Dated. October 3-1 1972 Patent No. 3 701 921 In ent r( Hans It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Page 1 below the headihg [301 Foreign Application Priority Data" change "1 Tovember 20, 1969" to November 10, 1969";

Signed and sealed this 10th. day of Jul 1 973 (SEAL) Attest:

EDWARD MELET-QHERJR. Rene Tegtmeyer ttesting Off ce-r j Acting Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 9 7'01 2 921 Dated OCCOb'eI 31 1972 Hans Wiedenmann Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Page 1, Below the heading I30] Foreign Application Priority Data" change November 20, 1.969" to November" 10 1969 Claim 1:, line 1, change envelop" "to GITI'VeJ- P 'T'Q This certificate supersedes Certificate of Correction issued July 10', 1973.

Signed and sealed this 27th day of November 1973.

C Attest;

RENE D. TEGTMEYER EDWARD M.,FLETCHER,JR.

' Acting Commissioner of Patents Attesting Officer FORM PO-1050 (10-69) USCOMM-DC song-Pee u.s. GOVERNMENT rmm'ngs OFFICE Into-'gpa-su, 

2. Lamp according to claim 1, wherein the interposed aluminum is a layer of aluminum foil of up to 0.1 mm. thickness.
 3. Lamp according to claim 1, wherein the thickness of the pinch-sealed molybdenum foils is about 15 to 60 Mu .
 4. Lamp according to claim 1, wherein the lamp has internally positioned elements and aluminum is interposed in welds between the pinch-sealed molybdenum foils and the elements positioned internally of the lamp.
 5. Lamp according to claim 1, wherein the elements of refractory metal include molybdenum and tungsten.
 6. Lamp according to claim 1, wherein the elements of refractory material include lead-in wires or base pins. 